Process for chlorinating copper sulfide minerals

ABSTRACT

A substantially dry intimate mixture of copper sulfide mineral concentrate and an added diluent material is contacted with at least a stoichiometric amount of chlorine relative to chlorinatable compounds of such materials at a temperature of between 300* and 400* C. to produce a reaction product containing water-soluble cupric chloride. Sulfur and iron values present in the mixture are substantially completely volatilized. Typical diluent materials are chlorinatable iron compounds, gangue materials, silica sand, and carbon. A portion of the diluent can be already present in the copper sulfide material, for example gangue components of a copper sulfide mineral concentrate, with the rest of the necessary diluent being added to form the mixture. The cupric chloride product recovered from the waterinsoluble residue in the reaction product as by means of water leaching is substantially uncontaminated by sulfur or iron values.

United States Patent, [191 Spreckelmeyer Aug. 27, 1974 PROCESS FORCHLORINATING COPPER SULFIDE MINERALS [75] Inventor: Bernhard W.Spreckelmey'er,

Porz-Urbach, Germany [73] 'Assignee: Kennecott Copper Corporation,

New York, NY.

[22] Filed: Apr. 7, 1971 [21] Appl. No.: 131,947

[52] US. Cl 423/40, 423/493, 423/469 [51] Int. Cl..... C01g 3/04, COlg49/10, COlb 17/45 [58] Field of Search 23/97, 87 R; 423/493, 40, 423/469[56] References Cited UNITED STATES PATENTS 846,657 3/1907 Frolich 23/97UX 1,078,779 11/1913 Forland 23/97 X 1,198,519 9/1916 Bradley 23/971,353,773 9/1920 Marsh 23/97 X 1,917,231 7/1933 Bacon et a1 23/97 X2,987,378 6/1961 Thoma 23/97 X 3,117,860 1/1964 Bjerkerud et al. 23/97 XPrimary Examiner-Edward Stern Attorney, Agent, or FirmPhilip A.Mallinckrodt [57] ABSTRACT A substantially dry intimate mixture ofcopper sulfide mineral concentrate and an added diluent material iscontacted with at least a stoichiometric amount of chlorine relative tochlorinatable compounds of such materials at a temperature of between300 and 400 C. to produce a reaction product containing watersolublecupric chloridev Sulfur and iron values present in the mixture aresubstantially completely volatilized. Typical diluent materials arechlorinatable iron coinpounds, gangue materials, silica sand, andcarbon. A portion of the diluent can be already present in the coppersulfide material, for example gangue components of a copper sulfidemineral concentrate, with the rest of the necessary diluent being addedto form the mixture. The cupric chloride product recovered from thewater-insoluble residue in the reaction product as by means of waterleaching is substantially uncontaminated by sulfur or iron values.

3 Claims, 1 Drawing Figure DILUENT MATERIAL (FeS gangue, sand charcoal)REACTION 300C. T

GASEOUS MlXTURE VESSEL OF AND Feel,

RESIDUE CONTAINING WATER-SOLUBLE CuC RECOVERY OF cuci,

COPPER SULFIDE MATERIAL (e.g. CuS, CuS Cu s, Cu FeS DILUENT MATERIAL V Fz 29r192?l..2"99915 v c HLORINE GASEOUS MXTURE REACTON VESSEL s c AND m300C. TO 400C RESIDUE CONTAINING WATER SOLUBLE CuCl RECOVERY OF CuClINVIENTOR. BERNHARDY W SPRECKELMEYER M AT TORNEYS PROCESS FORCHLORINATING COPPER SULFIDE MINERALS BACKGROUND OF THE INVENTION 1.Field This invention relates to the extraction of copper values fromcopper sulfide materials, and more particularly to a process forchlorinating copper sulfide to produce water-soluble cupric chloride.

2. State of the Art Many processes have been proposed for treatingcopper sulfide ores, particularly in the form of concentrates, toextract the copper values contained therein. In addition to theconventional processes for smelting copper-bearing concentrates, variousproposals have been made for exposing copper sulfide materials tochlorine. Some of the chlorination processes are known as wet processesbecause they treat a copper sulfide material in the form of an aqueousslurry. Other processes treat a copper sulfide material in a dry state,but convert the copper values to water-insoluble-cuprous chloride (Cu Clcontaminated with insoluble iron and sulfur values. Still otherprocesses employ a combination of dry and wet extraction techniques. Allof the known chlorination processes suffer from at least two majordisadvantages. We have found that, in the absence of sufficient diluentmaterial, such as iron pyrite or gangue, the chlorination of the coppervalues is incomplete, leaving insoluble copper values in the reactionproduct. Moreover, significant amounts of the copper values which areextracted are volatilized and lost at reaction temperatures of over 400C. The reaction product also contains appreciable amounts ofcontaminating sulfur and iron values which are separated from the coppervalues only with difficulty and at great expense.

OBJ ECIIVE It was an objective in the development of this invention toextract substantially all the copper values con tained in a coppersulfide material as a cupric chloride product containing substantiallyno contaminating sulfur or iron values.

SUMMARY OF THE INVENTION In accordance with the invention, copper valuesare extracted from copper sulfide minerals, such as ore concentrates, bycontacting a dry, intimate mixture of such a copper sulfide mineral anda diluent material with at least a stoichiometric amount of chlorine ata temperature of between about 300 C. and about 400 C. The reactionextracts substantially all of the copper values and produces a reactionproduct containing water-soluble cupric chloride (CuCl which can beleached from the residue and recovered by conventional means. Sulfur andany chlorinatable iron values present in the mixture are substantiallycompletely volatilized as chlorides during the reaction.

Diluerit materials suitable for use in the process comprisechlorinatable iron values, such as iron pyrites (FeS gangue materialsnormally present in an ore, silica sand, carbon, etc. A portion of thediluent material utilized as such in the mixture can be initiallypresent as gangue in the copper sulfide material itself. Under suchcircumstances, only the additional diluent necessary for the reaction isadded to the sulfide material to form the desired mixture. Completeconversion of copper values to cupric chloride is achieved if sufiicientdiluent, such as a chlorinatable iron compound, is added to the coppersulfide material to form a mixture having a molar ratio of at least 1:1iron to copper. The other diluents are freely interchangeable with theiron either in part or in whole. The utilization of diluent materialsother than iron compounds substantially eliminates any volatilizationloss of copper values. Volatilization of the sulfur values, and ironvalues if present, permits the direct recovery of at least 99.9 percentof the cupric chloride in the reaction product by water leaching. I

THE DRAWING The best mode presently contemplated for carrying out theinvention is illustrated in the accompanying drawing, in which thesingle FIGURE is a flowsheet showing the process as applied to coppersulfide materials to produce uncontaminated cupric chloride.

DETAILED DESCRIPTION OF THE ILLUSTRATED PROCEDURE As illustrated in theattached flowsheet, the process of the invention is carried out byreacting a dry, intimate mixture of a copper sulfide material and adiluent mineral with at least a stoichiometric amount of chlorine gas ata temperature of between 300 and 400 C. to react with substantially allcontained copper, iron, and sulfur values to produce a reaction productcontaining uncontaminated, water-soluble cupric chloride. The resultingiron and sulfur chlorides leave the reaction in the gaseous state.

The process can be used with minerals, such as covellite (CuS),chalcocite (Cu S), digenite (Cu s), and bornite (Cu FeS in the form ofan ore concentrate. The material can be in any physical form or have anyparticle size capable of reacting with chlorine. The most efficientresults are obtained if the sulfide material is crushed to a fineparticle size, as it is in the usual ore concentrate, to permit rapidand complete reaction between the copper sulfide and the chlorine.

It is essential that a diluent material be present to ensure completeconversion of the copper values to cupric chloride. It has been foundthat chlorinatable iron compounds (such as iron pyrites), ganguematerials, silica sand and activated carbon are all effective in theprocess and are interchangeable with each other. Part of the diluentmaterial may be initially present in the concentrated copper sulfideminerals to be processed. In such a situation, the remaining diluent isadded to the copper sulfide concentrate to form the necessary mixture.For example, bornite (Cu FeS contains both copper and iron values. Ifthe reaction with the chlorine is to proceed to completion with thechlorination of substantially all of the copper and iron values, themolar ratio of iron to copper should be at least 121. Accordingly,additional chlorinatable iron-bearing material, such as iron pyrite, ismixed with the bomite to achieve the desired molar ratio. bower molarratios will be effective in providing correspondingly smaller amounts ofwater-soluble copper chlorides and volatile iron chloride.

Similar results are attained in the process when activated carbon,quartz sand, or gangue materials, such as that contained in coppersulfide mill heads or tailings, are employed as the diluent material inplace of, or in addition to, the iron-bearing material. Weight ratios ofa copper sulfide mineral, such as covellite, to quartz sand, gangue, oractivated charcoal of from 1:1 to 1:4 were found to provide virtuallycomplete chlorination. If less than complete chlorination is acceptablefor the particular conditions or materials to be employed, lower ratioscan be used to provide acceptable results with less than completeconversion of the copper values to cupric chloride.

The process produces not only cupric chloride as a water-solubleproduct, but also results in the formation of volatile by-products,sulfur chloride (S' Cl and ferric chloride (FeCl The volatile chloridecompounds are drawn off from the reaction and do not remain in thereaction product as contaminants. The presence of diluent materials,such as water-insoluble gangue, sand, or charcoal in the reactionproduct does not appreciably affect the solubilization of cupricchloride. Recovcry of the cupric chloride from the reaction product iseasily brought about by conventional means, such as water-leaching,followed by separation of the pregnant solution from the residue andprecipitation of the copper values from solution.

As noted in the accompanying examples, the reaction is best carried outunder controlled conditions in which such variables as the temperatureand the amount of chlorine can be regulated. For example, the reactioncan be carried out in a closed reaction vessel which has been flushedwith nitrogen before introducing the chlorine.

The chlorine used in the process is in the form of a gas and must bepresent in an amount at least stoichiometrically equivalent to theamount of copper, sulfur, and iron present in the mixture to besubjected to chlorination. Preferably, greater than stoichiometricamounts of chlorine are used. Less than stoichiometric amounts result inthe formation of the intermediate,

waterdnsoluble cuprous chloride (Cu Cl which remains as a contaminant inthe reaction product. The chlorine can be introduced in any conventionalmanner, including countcrcurrent to the sulfide material or flowing overa stationary bed of the copper sulfide in a closed reaction vessel. Thepresence of air or nitrogen mixed with the chlorine is acceptable andhas no deleterious effects. However, water or water vapor isundesirable.

The chlorination reaction is exothermic and requires the introduction ofheat only to start the reaction. The temperature of the reaction ismaintained below about 400 C. to reduce the amount of volatilization ofcopper values and to avoid the formation of acid-soluble cuprouschloride. The temperature is held above about 300 C. to ensure completevolatilization of ferric chloride and the complete chlorination of thecopper values. A temperature variance of about 34 outside the range of300 400 C. is acceptable. As a result of the exothermic nature of thereaction, it is preferred that the starting temperature lie within therange of about 300 to 360 C., although higher starting temperatures canbe used. At a starting temperature of about 330 C. the maximum reactiontemperature can increase to a point within the range of about 380 C. toabout 400 C. Depending on the size equipment employed in the process andthe ability of the equipment to conserve heat, provision will often haveto be made for cooling the reaction to maintain a temperature below 400C.

The temperature of the reaction is maintained as low as possible below400 C. (but above 300 C.) to reduce the amount of volatilization ofcopper chloride. Moreover, the intermediate cuprous chloride (Cu Clmelts at about 430 C. The presence of molten Cu Cl would hinder furtherchlorination if the temperature were permitted to reach that level.Under optimum conditions, as little as 1 percent of the original coppervalues are volatilized, and 99.9 percent of the copper chlorides in thereaction product are recovered as water-soluble cupric chloride. Theselection of the precise temperature within the 300 400 C. range isinfluenced by four factors: (1) the completeness of the chlorination ofcopper values; (2) the volatility of copper values during the reaction;(3) the volatility of ferric chloride; and (4) the formation ofundesirable cuprous chloride. These factors are also influenced by thetype of diluent material employed, as has been explained hereinbefore.

The following examples illustrate the process of the invention, and arenot intended to limit the scope of the invention.

Examples Forty-one tests were conducted employing mixtures of differentcopper sulfide materials and concentrations of iron-bearing materials,gangue, quartz sand, and activated carbon. The temperature of each testis shown in the accompanying tables in addition to the data showing thecompleteness of chlorination of the copper values, volatilization ofiron values and amount of copper values recovered from the reactionproduct. For each test, 20 grams, plus or minus 5 grams, of the startingmaterial were used. The chlorination took place in a closed chlorinationtube with an excess of chlorine gas for 270 minutes, plus or minus 30minutes. The data for tests using a variety of copper sulfide mineralsin their pure states are set forth in Table I. Table II provides thedata for three types of copper sulfide concentrates.

TABLE L-CHLORINATION OF CHALCOCI'IE, DIGENITE, AND COVELLITE: INFLUENCEOF DILUENT MATERIALS ON CHLO RINATION Soluble copper, Starting materialTest data tem- Chlorinated res- Residue leach Cu percent of perature, C.idue, percent Volatilized distribution in- Cu.tm:l: copper, Tes Ratiopercent of Resi- No Constituents, weight ratio Fe/Cu Tum max- Cu Fe Cum"H2 H 1 due 1 CuzS 0.06 228 378 52. 2 1. 15 5. 56 2 CuaS .07 326 38146.8 1. 20 .52 0. 85 03.0 3-.. CuaS 07 336 406 48.3 1.30 .01 1. 42 88.C1113 .06 343 432 53.3 1.50 .004 .35 40.3 5.. CUIS'i'FOS}, 1:0.75- 07340 305 44. 8 .40 .04 1. 2.) 00.02 6-. cuis-t-resl, 1:1.5 1. 18 326 37042. 2 1. 80 04 1. 54 90.00 7-. C'lhS-l'FeS- 141.5,. 1. 336 381 44. 0 6004 1. 84 90. 98 8.. CurS+FeS1, 1:1.5. 1.15 351 400 44. 6 40 .03 2.10 90.00 0 CuaS-l-Arthur Gen. Mill Heads, 1:1 12 327 404 27. 2 1. .01 15 00.88 07 10 CmS+Arthur Gen. Mill Tails, 1:! 11 3'26 300 27. 2 1. 01 1309.85 11 CuaS+Cherc0aL 4:1 07 327 418 34. 3 1. 00 62 07 09. 04 .27 90- 7J. 0 12 CuzS+Quartz Send I; 1:1 08 331 398 27.4 .50 .03 .02 99.97 .0)..01 00.7 3

Soluble copper, Residue leach Cu percent of volatilized distribution in-Cumml:2%,

copper, percent of Resi- Cumin E HCI due 63267 300 aaLL r m Solublecopper,

percent of startd:2%

Residue Cu Cu 1 nnwmi snmwwng C. Tests and a high percentcomplete andthe volatilization of C. This indicated an upper tempera- C. yieldedincomplete reacfurthermore, a close connection ben content and theamount of volatilized CHLORINATION -Continued Starting material Testdata tem- Chlorinated resperature, C. idue, percent Ratio Fe/Cu Tu -t TC11 TABLE I.-CIILORINATION OF CHALCOCITE, DIGENITE, AND COVELLITE:INFLUENCE OF DILUENT MATERIALS ON Constituents, weight ratio f. S H mm mm m m ma 6 .m wev e1 m u i t d m n h H h g a nC d n e .m a m m? m e m on c o m e n m s m t 0% 00 I Ne n e a O a 85 I cm m n c H 2. w eflm m i du D. .m n N MD. n n d n n mwmm n m hi e n t m c m m wmmwsmww mm m neamwmummmummmm t w 7 n m e w d m o m s a .W...9 MW H n :12 m C m a e s am New m w mmmw. w mam mmwwwmwmw E am e. menmmmmmmmwmmmmmnaa m o s a a Na r a s m m P WM 1 wnwnwmhmw m R H nwwwm i awwww s mm m a mm mm w Pmm Ra a 6d m P v e mm .nnnnmmm m m mm mmmmmmmmmmmnmnmmaaam m mHJfw i me n wdmm gwwm W E 1111111112334 12 mum mmm m m G mwm t adpmmmfi w w .m N o p m0 g e o e o o c d n s e m m m w m w v a 0 n m N m c c a n w w o e m d ow Z P a ms o t mwmmwmnm E a mmwmmewmmamnmnmm r m m e1 We a m a m m. e na m Mm e O m.- m9we wt.wn W F c s Pn d .u wmwema w L we emwmnnmwwmmemmwmem m n m r w m 7 m a 0 m nm m w W aarrramrarrirrr Ma waneeyrmdornneinefie a R mm u ovoasanfissseeasaee m m mm m m m% m e mmmmmfim m We. m engage. m o mmmummwnwnnanunnaaw .m w mmm w mMmmm ummmw W P82362733869 6 6376 mmmnwmmm m m w maawnmnwmwwinmmmwnfia u m w to W a T WF m e n & .bd 6 N 0 d n 876637 670 4.2 6 0 h e h 0 2 O r. n mmammwmm N mm wwnnnamwaanmwmsmwnmwm mm mummy m a m w m m mm T N m m m a m m M f woenwwww u .3 wmmwmnewaneeneeaaaaaw m m aflN m o e a e m N MW ..L. E I-lt .1 R r m d s a m m m w m a n Z h o W o m .m g e l e c N 1 o a Q s 00L .1 mdCm mm n. m mw H u u u m4a c m smm E ssw m a J n k mnw m mm m a a231 u n U a .co P r a a m m I m .naemmwwwew m m n t u .m m m m m m m mmm dw m m m m B m u n u u N Tl ft m mbtm hm P t m m m m u u n n "aw mmmmfl m w mmm P a .1 n f ILLIM m mm u m" m+. m wm mw m dddd M h" u "H Hme mp eomo e H nnnnflmus S .W H .I r. O h m d C S mama T u e o a n u a na a c e t r w n f a ZZZZ" N u N "N e mem o m we m0 W rnmmmn w we on een. t H f w q n 48 n n M M. M Ma en noo 6 9 awe wa sfi .m mm a m "m "anmmmnn m m mmwmwm .++++s s" fie m 0 :nsume uu o SSSSAAHT m m cdd d 0 nb.l .mmmmmm u o 0 m k h w m mm 0 HCCCCCCGCU Cc 0 o .C. a f. s a o ffl w mwe d N n .fi ew+ mmm mm( w e I234 a n W 1.1.1.1.1. w m" .m wm mammeTmk wm mnmmumwm TN mwaasamawmmmanenmawfi ocpcnwsd nwnd 5 Test No.

tested, the amount of volatilized copper was propor- 55 tional to theamount of iron volatilized in the reaction,

and was independent of the kind of chlorinated material employed at agiven test temperature. A complete chlorination of the copper values tocupric chloride is possible in the presence of either a high iron or ahigh gangue, sand, or charcoal content. However, increasing the gangue,sand, or charcoal content and decreasing the iron content has theadvantage of lowering the percentage of copper volatilized during thereaction.

Whereas this invention is here illustrated and described with respect tocertain preferred procedures thereof, it is to be understood that manyvariations are For all mixtures and tests with a starting temperature ofabout 325 C., a complete chlorination to cupric chloride was achievedand more than 99.5 percent of the residual copper was found in the waterleach. These results indicate a high influence of the gangue on the 0completeness of the reaction and on the formation of cupric chloride.

In Table II, the copper sulfide concentrates, Nos. 1, II, and III, weresuccessfully chlorinated with starting temperatures between 300 and 400C. to form cupric chloride. Only the chlorinated product of concentrateNo. I contained a considerable amount of cuprous possible withoutdeparting from the inventive concepts particularly pointed out in theclaims.

I claim:

1. A process for treating concentrated copper sulfide minerals insubstantially dry condition for the recovery of substantiallyuncontaminated copper values in the form of water-soluble cupricchloride, comprising mixing a copper sulfide mineral concentrate withcarbon in the form of activated charcoal, contacting the mixture with atleast a stoichiometric amount of chlorine gas based on the amount ofchlorinatable material present in the mixture at a temperature betweenabout 300 C. and about 400 C, the added carbon material being sufficientin amount to be effective for the formation of a

2. A process as set forth in claim 1, wherein the chlorine gas is passedin a continuous stream through the mixture in a closed system.
 3. Aprocess as set forth in claim 1, wherein the starting temperature of thereaction is between about 300* C. and about 360* C.